Two-dimensional modulated structure in quenched Ga ₂ Te ₃ with the defect zincblende lattice

Ga 2 Se 3 and Ga 2 Te 3 crystallize to the cubic zincblende structure, where 1/3 of the cation sites are vacant. Semiconductors with large concentrations of vacancies are actively studied due to their potential for application. In this article, the modulated structure in quenched Ga 2 Te 3 has been studied using single crystal X-ray diffraction data. Analysis of satellite reflections observed at q = (0.06, 0.06, 0.00) c revealed that the real structure is tetragonal and belongs to the superspace group I <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <m:mrow> <m:mover accent="true"> <m:mn>4</m:mn> <m:mo>̅</m:mo> </m:mover> </m:mrow> </m:math> ̅4 m 2( α , 0, 0)0(0, α , 0)0. The structure is characterized by an occupational modulation caused by Ga vacancies, and accompanying displacement modulations of both Ga and Te atoms. The origin of the displacement modulations was discussed and attributed to the expanding motions around the Ga vacant sites. These motions are concave downward (toward − z ) along [110] c , while they are upward (toward + z ) along [−110].